1. InterDigital, Inc. Submission doc.: IEEE 802.11-16/0911r1 July 2016 Link Level Performance Comparisons of Open Loop, Closed Loop and Antenna Selection for SU-MIMO Date: 2016-07-25 Slide 1 Authors:

2. InterDigital, Inc. Submission doc.: IEEE 802.11-16/0911r1 July 2016 Introduction TGay has agreed that 11ay will support SU-MIMO [1] In [2], we have shown 11ay system throughput benefits from CL SU-MIMO, using theoretical achievable sum rate. Still further studies are required to see whether benefits exist for SU-MIMO with equal MCS among spatial streams with single CRC. In this contribution, we performed SU-MIMO link level simulations based on 11ay channel model for analog beamforming, and baseband open loop, closed loop, antenna selections precoding as a follow-up study. Slide 2

3. InterDigital, Inc. Submission doc.: IEEE 802.11-16/0911r1 July 2016 Baseband Precoding Methods Open loop: Use the first N ss columns of an orthogonal matrix as precoding matrix cross all antennas* No channel knowledge needed at transmitter Closed loop: Use SVD based on the time domain channel matrix of the strongest path Full Channel State Information (CSI) knowledge at transmitter Antenna selection: Select the best N ss Tx antennas which gives the best total Rx power Partial CSI knowledge at transmitter * One PAA with dual polarization is considered as two antennas Slide 3

4. InterDigital, Inc. Submission doc.: IEEE 802.11-16/0911r1 July 2016 Simulation Assumptions Based on 11ad SC PHY Spatial stream parser: MCS index is the same for all streams per PPDU, single CRC per PPDU MMSE receiver Conference room (CR) scenario in 11ay/ad channel model STAs are randomly placed on a 1×2.5 m table in the center of the CR, 1m above the floor AP is positioned at x=1.5, y=0.5, z=0.1m below the ceiling Ideal channel estimation at receiver Detailed assumptions can be found in the appendix b1b2b3b4b5b6 b1b3b5 b2b4b6 Encoder Output Bits Stream 1 Stream 2

5. InterDigital, Inc. Submission doc.: IEEE 802.11-16/0911r1 July 2016 Simulated SU-MIMO Configurations Beamforming implemented in all configurations Analog beamforming: Using phase shifter at each antenna to align Tx and Rx beams Digital beamforming: Spatial streams are precoded (as described in slide “Baseband Precoding Methods”) and distributed to all antennas We simulated the following SU-MIMO PAA configurations [3] Slide 5 Configuration #2 2x2 channel, 1 PAA with dual polarization, on each side Configuration #4 4x4 channel, 2 PAAs with dual polarization on each side Configuration #4 @Tx, Configuration #2 @Rx 4x2 channel, 2 PAAs with dual polarization on Tx side, 1 PAA with dual polarization on Rx side

6. InterDigital, Inc. Submission doc.: IEEE 802.11-16/0911r1 July 2016 TX Conf #4/RX Conf #2, Nss=2, AP-STA Tx Rx Slide 6 PER performance for CL is significantly better than OL In OL, the signals of the same polarization from different Tx PAAs cause interference at RX, while in CL, these signals are combined coherently at RX.

7. InterDigital, Inc. Submission doc.: IEEE 802.11-16/0911r1 July 2016 Conf #2, Nss=1, STA-STA TxRx Slide 7 PER performance for CL and antenna selection are better than OL Virtual channel after analog beamforming provides enough spatial/polarization separation CL is slightly better than antenna selection however it requires much more channel knowledge In this case the number of stream is less than the rank of the channel. There is extra degree of freedom for CL to explore

8. InterDigital, Inc. Submission doc.: IEEE 802.11-16/0911r1 July 2016 Conf #2, Nss=2, STA-STA Slide 8 Tx Rx Slide 8 CL and OL have similar PER performances The channels between different polarizations are close to orthogonal. The OL/CL have similar performance when Nss is equal to the rank of the channel In this case the number of stream is the same as the rank of the channel. There is no extra degree of freedom for CL to explore.

9. InterDigital, Inc. Submission doc.: IEEE 802.11-16/0911r1 July 2016 Conf #4, Nss=2, STA-STA Slide 9 TxRx CL and antenna selection are significantly better than OL Virtual channel after analog beamforming provides some spatial/polarization separation CL is slightly better than antenna selection however it requires much more channel knowledge In this case the number of stream is less than the rank of the channel. There is extra degree of freedom for CL to explore

10. InterDigital, Inc. Submission doc.: IEEE 802.11-16/0911r1 July 2016 Slide 10 Conclusion We demonstrated that CL SU-MIMO achieves up to 20 dB performance gain compared to OL SU-MIMO, particularly for the case Ntx > Nss Antenna selection provides better performance for SU-MIMO than OL while requiring significantly less feedback than CL

11. InterDigital, Inc. Submission doc.: IEEE 802.11-16/0911r1 July 2016 Slide 11 References 1.Carlos Cordeiro, “Specification Framework for TGay”, IEEE 802.11- 15/01358r4 2.Rui Yang, et al, “Open Loop vs Closed Loop SU-MIMO for 11ay”, IEEE doc. 11-15/0642r1 3.A. Maltsev, et al, “Channel models for ieee 802 11ay”, IEEE doc. 11- 15/1150r4 4.R. Maslennikov, et al, “Implementation of 60 GHz WLAN Channel Model,” IEEE doc. 11-10/0854r3.

12. InterDigital, Inc. Submission doc.: IEEE 802.11-16/0911r1 July 2016 APPENDIX Slide 12

13. InterDigital, Inc. Submission doc.: IEEE 802.11-16/0911r1 July 2016 AP/STA Orientation For STA-STA scenarios, STA are placed randomly at the same height on the conference room table. Each STA is randomly rotated around z- axis with LOS path not blocked For AP-STA scenario, STA is placed at a plane 1.9m below AP on the conference room table. Random rotation around z-axis between STA/AP. Slide 13

14. InterDigital, Inc. Submission doc.: IEEE 802.11-16/0911r1 July 2016 Channel parameters Ray generation between each TX/RX PAA pair is based on the parameters in Table 2 of [4], with exception of LOS probability set to 1 For SU-MIMO configuration #2, TX/RX analog beamforming for both polarizations are based on the LOS direction Each PAA has 2x8 elements For SU-MIMO configuration #4, TX/RX analog beamforming for both polarizations of PAA#i are based on the LOS direction between TX PAA#i ↔ RX PAA#i Each PAA has 2x8 elements For SU-MIMO TX configuration #4 and RX configuration #2 TX analog beamforming for both polarizations of PAA#i are based on the LOS direction between TX PAA#i ↔ RX PAA#1 RX analog beamforming for both polarizations of PAA#1 are based on the direction between RX PAA#1 ↔ middle point of TX PAAs TX PAA has 2x8 elements RX PAA has 2x2 elements Channel bandwidth 1.76 GHz, center frequency 60GHz Distance between antenna elements 0.0025m Distance between center of PAAs 10cm Slide 14